JP4267324B2 - Superconducting filter device and radio reception amplifying device - Google Patents

Superconducting filter device and radio reception amplifying device Download PDF

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JP4267324B2
JP4267324B2 JP2002566856A JP2002566856A JP4267324B2 JP 4267324 B2 JP4267324 B2 JP 4267324B2 JP 2002566856 A JP2002566856 A JP 2002566856A JP 2002566856 A JP2002566856 A JP 2002566856A JP 4267324 B2 JP4267324 B2 JP 4267324B2
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pilot signal
superconducting filter
antenna
noise amplifier
refrigerator
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JPWO2002067446A1 (en
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学 甲斐
透 馬庭
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/203—Strip line filters
    • H01P1/20327—Electromagnetic interstage coupling
    • H01P1/20354—Non-comb or non-interdigital filters
    • H01P1/20372—Hairpin resonators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/03—Constructional details, e.g. casings, housings
    • H04B1/036—Cooling arrangements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/825—Apparatus per se, device per se, or process of making or operating same
    • Y10S505/842—Measuring and testing
    • Y10S505/847—Thermal
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/825—Apparatus per se, device per se, or process of making or operating same
    • Y10S505/888—Refrigeration

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  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)

Description

技術分野
本発明は移動体通信の基地局に用いる超伝導フィルタ装置及び超伝導フィルタを備えた無線受信増幅装置に係り、特に、冷凍機の異常を速やかに検出することが可能な超伝導フィルタ装置及び超伝導フィルタを備えた無線受信増幅装置に関する。
背景技術
一般に、通信用フィルタで急峻な遮断特性を得るためにはフィルタの段数を大きくしなければならない。しかし、その分、通過帯域における損失が大きくなる問題が発生する。そこで、超伝導体が通常の金属に比べて抵抗が２〜３桁低いことに着目し、フィルタの導体として超伝導体を用いて通過帯域における損失を極力小さく抑えるようにした超伝導フィルタが実用化されている。かかる超伝導フィルタは、近年、移動帯通信における周波数の有効利用、加入者容量の増加、基地局カバーエリアの増大等を目的として注目を浴びている。超伝導フィルタの超伝導体材料として臨界温度（Ｔｃ）＝９０Ｋ程度のＹＢＣＯ（Ｙ−Ｂａ−Ｃｕ−Ｏ）が知られており、特性が安定するＴｃ＝７０Ｋ程度で使用されている。
図１８は超伝導フィルタを備えた従来の無線受信増幅装置の構成図である。超伝導フィルタ（ＳＣＦ）１と低雑音増幅器（ＬＮＡ）２はコールヘッド（冷却端）４上に固定され、真空容器３内に収容されている。コールヘッド４は冷凍機５により冷却されるようになっておリ、超伝導フィルタ１、低雑音増幅器２はこのコールヘッド４を介して冷凍機５により冷却されてＴｃ＝７０Ｋで動作するようになっている。真空容器３及び冷凍機５は屋外に設置できるように筐体６の中に配設され、筐体６及び真空容器３に設けた端子７ａ、７ｂ間並びに８ａ，８ｂ間は同軸ケーブル９ａ，９ｂにより接続され、又、端子７ｂ→超伝導フィルタ１→低雑音増幅器２→端子８ｂ間も同軸ケーブル９ｃにより接続されている。
超伝導フィルタ１は図１９（Ａ），（Ｂ）に示すように、厚さｔ＝０．５ｍｍのＭｇＯ基板１ａ上にフィルタ電極１ｂとｎ段（図ではｎ＝５）のλ／２共振器１ｃをＹＢＣＯ膜でパターニングし、アルミ合金パッケージ１ｄで密封した構成を備えている。パッケージ１ｄは電磁界の漏れを防ぎ、これにより均一にフィルタ基板１ａを冷却する。尚、図１９（Ａ）はパッケージの上蓋１ｅを取り除いた平面図、図１９（Ｂ）は（Ａ）におけるＡＡ断面図である。又、１ｆ，１ｇは同軸コネクタ、１ｈは厚さ０．４μｍのＹＢＣＯ膜で形成したグランドである。
真空容器内における電気接続構成は図２０に示すようになっており、例えば２系統の無線受信増幅装置が形成されている。超伝導フィルタ１，１′は７０Ｋの極低温に冷却されると所定の通過帯域特性を示し、入力端子７ｂ，７ｂ′から入力する受信信号に含まれる信号のうち該通過帯域成分を出力する。低雑音増幅器（ＬＮＡ）２，２′は超伝導フィルタ１，１′を通過した信号を増幅して出力端子８ｂ，８ｂ′より送出する。低雑音増幅器２，２′は図２１（Ａ），（Ｂ）に示すゲイン特性、雑音指数特性を備えている。実線は常温時（＝２３℃）、点線は７７Ｋの極低温時の特性であり、極低温にするとゲインが２ｄＢ程度上昇し、かつ、雑音指数（Ｎｏｉｚｅ Ｆｉｇｕｒｅ）が減小することがわかる。すなわち、低雑音増幅器２，２′は常温より極低温で使用する方が好ましい。
以上より、超伝導フィルタ１は真空容器３内に納められ、冷凍機５によってたとえばＴ＝７０Ｋといった極低温に冷却されて動作する。また、受信した信号を所定のレベルまで増幅する低雑音増幅器（ＬＮＡ）２も極低温化すると雑音指数を小さくできるので、超伝導フィルタ１と同時に冷却するのが一般的である。アンテナ（図示せず）により受信された信号はアンテナフィーダを介して入力端７ａから筐体６に入力され、同軸ケーブル９ａ，９ｃを伝播し、必要な周波数帯の信号だけが超伝導フィルタ１によって取り出され、低雑音増幅器２によって所定の信号レベルまで増幅され、出力端８ａから出力される。
移動体通信システムにおいて、図１８に示す無線受信装置はビルの屋上といった屋外に設置され、真夏などでは高温多湿の悪環境下に置かれる。このように非常に過酷な条件にありながら、無線受信装置は例えば数万時間といった長時間安定運転の信頼性が求められる。しかし、冷凍機５には多くの摺動部分が用いられるため、機械的に故障してしまう可能性がある。冷凍機５が故障すると、たとえばＴ＝７０Ｋに保たれていた温度が当然上昇してしまい、超伝導フィルタ１が本来の機能を果たせなくなり、通信不能という状態に陥ってしまう。そこで、冷凍機に故障が発生した場合、該故障を即座に検出して通報する機能あるいは故障を軽微の段階で検出して通報する機能が必要である。従来は真空容器内における温度を測定し、該温度が設定温度以上になったか監視することで冷凍機の異常を検出するものがあるが、装置が大がかりになり、重量も増加し、小型軽量化の要求にマッチしない問題がある。
以上より、本発明の目的は、冷凍機の障害を素早く、確実に検出でき、しかも、小型軽量化が可能な超伝導フィルタ装置や無線受信増幅装置を提供することである。
本発明の別の目的は、冷凍機の障害検出及び障害の程度を検出できる超伝導フィルタ装置及び無線受信増幅装置を提供することである。
本発明の別の目的は、冷凍機、低雑音増幅器のいずれに障害が発生したのか、あるいは両方に障害が発生したのかを確実に検出できるようにすることである。
発明の開示
本発明の超伝導フィルタ装置は、極低温に冷却されたとき所定の通過帯域特性を示す超伝導フィルタ、該超伝導フィルタを極低温に冷却する冷凍機、前記通過帯域外のパイロット信号を発生し、該パイロット信号を超伝導フィルタにアンテナ受信信号と共に入力するパイロット信号発生部、超伝導フィルタから出力する信号に含まれるパイロット信号のレベルに基づいて冷凍機の異常を判定する判定部を備えている。冷凍機に障害が発生して温度が上昇すると、超伝導フィルタの通過帯域が低周波側に移動し、パイロット信号周波数が超伝導フィルタの通過帯域内に入り、パイロット信号が超伝導フィルタを通過する。従って、超伝導フィルタから出力する信号にパイロット信号が含まれているか監視することにより冷凍機の異常を検出できる。本発明によれば以下の効果が期待できる。
（１）冷凍機の障害を素早く検出でき、しかも、超伝導フィルタ装置の小型軽量化が可能である。
（２）パイロット信号発生部を受信アンテナの近傍に設けることにより、例えば、パイロット信号放射アンテナを受信アンテナ近傍に設けることにより、損失なくパイロット信号を受信信号に挿入して超伝導フィルタに入力できる。
（３）アンテナフィーダ線にアイソレータを挿入することにより、パイロット信号が超伝導フィルタで反射されてもアンテナより空間に放射されないようでき、これにより他の通信系に干渉波とならないようにできる。
（４）超伝導フィルタから出力する信号に含まれるパイロット信号のレベルを検出し、該検出レベル波形に基づいて、例えば、レベル変化の割合に基づいて障害の程度を判断することができる。
（５）周波数の異なる２波のパイロット信号を発生して超伝導フィルタに入力し、判定部において各パイロット信号のレベルを検出し、それぞれの検出レベル波形に基づいて障害の程度を判断することもできる。
（６）超伝導フィルタに低雑音増幅器を接続し、該超伝導フィルタと低雑音増幅器をともに極低温に冷却することにより、超伝導フィルタを通過する信号を低雑音増幅器で増幅して出力する無線受信増幅装置を構成できる。
本発明の無線受信装置は、極低温に冷却されたとき所定の通過帯域特性を示す超伝導フィルタ、超伝導フィルタより出力する信号を増幅する低雑音増幅器、該超伝導フィルタと低雑音増幅器を極低温に冷却する冷凍機、前記通過帯域外のパイロット信号を超伝導フィルタと低雑音増幅器の中間部に印加するパイロット信号印加手段、低雑音増幅器から出力する信号に含まれるパイロット信号のレベル低下を検出し、設定レベルまで低下したとき冷凍機の異常と判定し、該設定レベル以外のレベルまで低下した時低雑音増幅器の異常と判定する判定部を備えている。
冷凍機（超伝導フィルタ）及び低雑音増幅器がともに正常であれば、パイロット信号印加手段から印加されたパイロット信号の半分の電力部分は超伝導フィルタ方向に進み、残りの半分の電力に相当するパイロット信号部分は低雑音増幅器の方向に進む。超伝導フィルタが正常に動作してれば、パイロット信号は全て反射して低雑音増幅器方向に折り返され、結局パイロット信号の全電力が低雑音増幅器に入力する。一方、冷凍機の障害により温度が上昇するとパイロット信号は超伝導フィルタに吸収されて全て熱となり、低雑音増幅器に入力する電力は１／２になる。従って、冷凍機が正常時と障害時とでは低雑音増幅器から出力する信号に含まれるパイロット信号レベルが異なり、障害時には正常時より所定レベル低下する。以上より、低雑音増幅器から出力する信号に含まれるパイロット信号のレベル低下を監視し、所定レベルまで低下したとき冷凍機の異常と判定し、該所定レベル以外のレベルまで低下した時低雑音増幅器の異常と判定する。
又、別のパイロット信号を超伝導フィルタに入力し、低雑音増幅器から出力する信号に含まれる該パイロットの検出レベルに基づいて冷凍機の異常を検出する。このようにすれば、確実に冷凍機の障害を検出でき、しかも、超伝導フィルタと低雑音増幅器の中間部に印加したパイロット信号の受信レベル低下に基づいて、低雑音増幅器の異常を確実に判定することが可能となる。
発明を実施するための最良の形態
（Ａ）第１実施例
（ａ）全体の構成
図１は本発明の無線受信増幅装置の構成図である。超伝導フィルタ（ＳＣＦ）１１と低雑音増幅器（ＬＮＡ）１２はコールヘッド（冷却端）１４上に固定され、真空容器１３内に収容されている。真空容器１３の中は真空に保たれ、外気温度は遮断されている。コールヘッド１４は冷凍機１５により冷却されるようになっており、超伝導フィルタ１１、低雑音増幅器１２はこのコールヘッド１４を介して冷凍機１５により冷却されてＴｃ＝７０Ｋで動作するようになっている。真空容器１３及び冷凍機１５は屋外に設置できるように筐体１６の中に配設され、筐体１６、真空容器１３の端子１７ａ、１７ｂ間並びに１８ａ，１８ｂ間は同軸ケーブル１９ａ，１９ｂにより接続され、又、端子１７ｂ→超伝導フィルタ１１→低雑音増幅器１２→端子１８ｂ間も同様に同軸ケーブル１９ｃにより接続されている。
筐体１６の入力端子１７ａにはアンテナフィーダ３１を介して受信アンテナ３２が接続され、該アンテナにより受信された信号は入力端子１７ａを介して超伝導フィルタ１１に入力する。又、パイロット信号発生部３３はパイロット信号を発生し、信号結合器３４を介して該パイロット信号をアンテナ受信信号に重畳する。従って、パイロット信号はアンテナ受信信号と共に超伝導フィルタに入力する。このパイロット信号の周波数ｆｃは、７０Ｋの超伝導フィルタ１１の通過帯域外の周波数である。
筐体１６の出力端子１８ａにはパイロット信号検出部２１が接続され、低雑音増幅器１２から出力する信号にパイロット信号が含まれているか監視すると共にそのレベルを検出するようになっている。パイロット信号検出部２１は、一部入力信号を取り込む方向結合器２１ａ、パイロット信号を通過する中心周波数ｆｃのバンドパスフィルタ２１ｂ、バンドパスフィルタ出力に基づいてパイロット信号レベルを検出するレベル検出部２１ｃを備えている。
（ｂ）本発明の原理
超伝導フィルタ１１は７０Ｋの極低温に冷却されると所定の通過特性Ｓ２１を示す。図２は超伝導フィルタ１１のＴ０＝７０Ｋにおける通過特性例であり、１９５０ＭＨｚ〜１９７０ＭＨｚの通過帯域を有している。超伝導フィルタ１１は、臨界温度（Ｔｃ）以下で動作させるが、図３（Ａ）に示すように温度をＴ＝Ｔ０→Ｔ１→Ｔ２（Ｔ０＜Ｔ１＜Ｔ２）と上昇させると、フィルタ通過帯域の中心周波数ｆ０がｆ００→ｆ０１→ｆ０２と低くなり、又、挿入損失Ｌｏｓｓが大きくなり、その変化の割合は臨界温度Ｔｃに近づくほど大きくなる。このため、温度により超伝導フィルタ１１の通過特性Ｓ２１は、図３（Ｂ）に示すように変化する。実際は、超伝導フィルタ１１の直後に低雑音増幅器１２が接続されているため、該低雑音増幅器１２の利得（ｇａｉｎ）分だけ信号が増幅される結果、総合の通過特性は温度により図３（Ｃ）に示すように変化する。
そこで、Ｔ＝Ｔ０（＝７０Ｋ）におけるフィルタ通過帯域外の周波数ｆｃを有するパイロット信号を超伝導フィルタ１１に入力しておく。ただし、パイロット信号の周波数ｆｃを通過帯域周波数より低くくなるように設定する。以上より、Ｔ＝Ｔ０においてパイロット信号周波数ｆｃは超伝導フィルタ１１の通過帯域外であるので、パイロット信号Ｓｆｃはフィルタ部分で反射され、低雑音増幅器１２には入力されない。
しかし、冷凍機１５の障害等により温度Ｔが上昇すると、図３（Ｃ）に示すように超伝導フィルタ１１の通過帯域が低周波側にずれ始め、次第にパイロット周波数ｆｃをフィルタ１１の通過帯域に含むようになる。この結果、パイロット信号Ｓｆｃがフィルタ１１を通過し始める（時刻ｔ＝ｔ１）。そして、温度がさらに上昇してパイロット周波数ｆｃが超伝導フィルタ１１の通過帯域に完全に入るまで（ｔ＝ｔ２）、パイロット信号の通過量が漸増する。パイロット周波数ｆｃが通過帯域に完全に入ればパイロット信号の通過量はほぼ一定となり、さらに、温度が大きくなってパイロット周波数ｆｃが超伝導フィルタの減衰域に入り始めると（ｔ＝ｔ３）、パイロット信号の通過量が漸減し、やがては完全に通過帯域外に入ると（ｔ＝ｔ４）通過量は零になる。この結果、パイロット信号検出部２１に入力するパイロット信号レベルは時間の経過に応じて図４に示すような波形になる。
以上より、閾値レベルＬＴＨを決めておき、これを上回れば、パイロット信号検出部２１は超伝導フィルタ１１の周波数特性（通過特性）が変化したと判定する。すなわち、パイロット信号検出部２１は検出レベルが閾値レベルＬＴＨを越えれば、冷凍機１５が故障して温度上昇が発生したと判定し、アラーム信号ＡＬＭを出力する。
（ｃ）冷凍機故障検出
超伝導フィルタ１１および低雑音増幅器１２を冷却端１４に固定し、真空容器１３の中で真空に保ち、外気温度を遮断する。超伝導フィルタ１１は、たとえば、酸化マグネシウムＭｇＯ基板上にＴｃ＝９０ＫのＹＢＣＯ超伝導体で９段、通過域１９２０ＭＨｚ〜１９４０ＭＨｚのフィルタパターンを構成し、サイズ５０×５０×１５ｍｍ程度の金属パッケージに収めて均一に冷却する。動作温度Ｔ０＝７０Ｋでは通過域の損失は０．１ｄＢ以下が実現できる。冷凍機１５には、図示しない外部から電源が供給され、図示しない駆動電源、温調機等によりフィルタ動作温度＝７０Ｋになるように駆動制御されている。これらはサイズ５００×５００×３００ｍｍ程度の筐体１６に収められ、ビルの屋上などの屋外に設置される。このため、真夏の昼間などは内部温度が６０℃〜８０℃になることもあり、冷凍機１５は過酷な条件に置かれても長時間安定運転することが求められている。
アンテナから受信された信号は、入力端１７ａから入力され、所望の周波数帯の信号だけが超伝導フィルタ１１を通過し、低雑音増幅器１２で増幅され、出力端１８ａから出力され、パイロット信号検出部２１を介して次段に送出される。ここで、フィルタ帯域外のパイロット信号（例えばｆｃ＝１９００ＭＨｚ）を受信信号に印加して入力端１７ａに入力させると、正常動作（Ｔ＝Ｔ０）している場合は、図３（Ｃ）に示したように、パイロット周波数ｆｃはフィルタの通過帯域外であるので、フィルタ部分で反射される。この結果、パイロット信号Ｓｆｃは低雑音増幅器１２に入力せず、該低雑音増幅器の出力信号にも含まれない。
しかし、冷凍機１５が故障して、超伝導フィルタ部分の温度が上昇すると、周波数特性が低周波側にずれ始め、パイロット信号は超伝導フィルタ１１を通過し始める。通過したパイロット信号は低雑音増幅器１２で増幅され、パイロット信号検出部２１に送られる。パイロット信号検出部２１は、パイロット信号成分だけを取り出し、一定時間毎のパイロット信号レベルをサンプリングする。冷凍機１５が故障すると、図４に示した検出レベルの時間波形が得られるから、パイロット信号検出部２１は検出レベルが閾値を超えると冷凍機故障というアラーム信号ＡＬＭを出力する。
以上のように、冷凍機故障時、パイロット信号検出部２１は一定時間毎のパイロット信号検出レベルをサンプリングして記録するが（図４参照）、温度の上昇速度に応じて検出レベルの時間波形の立上り、立下がり時の変化度合や閾値ＬＴＨを越えている時間幅が異なる。すなわち、重度の冷凍機故障の場合には、温度上昇速度が大きくなり図５のＣａｓｅ Ｂに示すように、検出レベルの時間波形の立上り、立下がりが急峻になり、閾値ＬＴＨを越えている時間幅が狭まくなる。一方、軽度の冷凍機故障の場合には、温度上昇速度が小さくなり図５のＣａｓｅ Ｃに示すように、検出レベルの時間波形の立上り、立下がりが緩やかになり、閾値ＬＴＨを越えている時間幅が広くなる。また、中度の冷凍機故障の場合には、図５のＣａｓｅ Ａに示すように、検出レベルの時間波形の立上り、立下がりの傾斜及び閾値ＬＴＨを越えている時間幅はＣａｓｅ Ｂ，Ｃの中間になる。以上より、Ｃａｓｅ Ａ〜Ｃの波形を識別する機構をパイロット信号検出部２１に搭載すれば、冷凍機の故障の程度がわかる。すなわち、障害の程度を、Ｃａｓｅ Ｂ＝重度、Ｃａｓｅ Ｃ＝軽度、Ｃａｓｅ Ａ＝平均的といったように分類することができ、障害の程度に応じて作業員派遣の優先順位をつけることができたり、故障原因特定のフィードバックにも役に立たせることが可能となる。
（Ｂ）第２実施例
図６は本発明の第２実施例の構成図であり、パイロット信号をアンテナ受信信号に挿入する好ましい構成を備えており、図１の第１実施例と同一部分には同一符号を付している。
パイロット信号は、第１実施例のように結合器などを用いてアンテナ受信信号に印加することができるが、低雑音増幅器１２より前の損失が増加し、雑音指数（ＮＦ）が増加してしまい、低雑音増幅器１２を冷却した利点を生かしきれない。そこで、図６に示すように受信アンテナ３２の近傍にパイロット信号発生装置３３を設置する。パイロット信号発生装置３３は、超伝導フィルタ１１の通過帯域外の周波数ｆｃのパイロット信号を発生する発振器３３ａと、該パイロット信号を受信アンテナ３２に向けて放射する指向性アンテナ３３ｂを備えているから、該アンテナ３３ｂを受信アンテナ３２に向け、かつ接近して配置する。この状態で発振器３３ａを発振するとパイロット信号が受信アンテナ３２に向けて放射され、アンテナ３２はパイロット信号を移動局からの信号と共に受信しアンテナフィーダ３１を介して信号入力端子１７ａに入力する。この結果、結合器のように余分な損失を含むことなくパイロット信号を移動局からの受信信号に重畳して入力端子１７ａに入力することができ、雑音指数（ＮＦ）を増加させることなく冷凍器の異常を検出することができる。
（Ｃ）第３実施例
図７は本発明の第３実施例の構成図であり、アイソレータ３５を受信アンテナ３２と筐体１６の入力端子１７ａ間に設けた構成を備えている点を除けば図６の第２実施例と同一構成を備え、同一部分には同一符号を付している。
冷凍機１５が正常動作している場合、超伝導フィルタ１１の通過帯域外のパイロット信号はフィルタ部分でほぼ全反射され、反射されたパイロット信号が逆にアンテナ３２から放射される。このとき、アンテナ３２が指向性をもち、利得がある場合、反射された信号レベルが大きくなって放射され、他の通信系にとって干渉波となる場合がある。そこで、第３実施例ではアイソレータ３５をアンテナフィーダ３１中に挿入することにより、超伝導フィルタ１１から反射されてきたパイロット信号を遮断する。第３実施例によれば、反射パイロット信号がアンテナから放射されて他の通信に悪影響を与えることはない。
（Ｄ）第４実施例
図８は本発明の第４実施例の構成図であり、第１、第２の２つのパイロット信号をアンテナ受信信号に挿入する構成を備えており、図６の第２実施例と同一部分には同一符号を付している。受信アンテナ３２の近傍に配置したパイロット信号発生装置３３は、周波数ｆＣ１の第１のパイロット信号Ｓｆｃ１を発生する発振器３３ｃ、周波数ｆＣ２（＞ｆＣ１）の第２のパイロット信号Ｓｆｃ２を発生する発振器３３ｄ、第１、第２のパイロット信号Ｓｆｃ１，Ｓｆｃ２を合成する合成部３３ｅ、第１、第２のパイロット信号を受信アンテナ３２に向けて放射するアンテナ３３ｆを有している。
長時間使用により冷凍機の冷凍能力が低下すると（軽度な故障）、冷凍機周囲温度の上昇により超伝導フィルタ１１の動作温度はＴ０（＝７０Ｋ）以上に上昇する。しかし、夜間になって冷凍機の周囲温度が室温程度まで下がると、超伝導フィルタ１１の動作温度はＴ０まで戻って正常動作する。一方、重度の故障では超伝導フィルタ１１の動作温度はＴ０（＝７０Ｋ）以上に上昇しっぱなしになり超伝導フィルタ１１は正常な動作をできなくなる。かかる故障の程度を検出できれば、故障程度に応じた対策を講じることが可能になる。
そこで、図９（Ａ）に示すように、Ｔ＝Ｔ０の超伝導フィルタ１１の通過帯域外の周波数ｆＣ１，ｆＣ２をそれぞれ有する２波のパイロット信号Ｓｆｃ１，Ｓｆｃ２を受信信号と共に超伝導フィルタ１１に入力し、各パイロット信号Ｓｆｃ１，Ｓｆｃ２のレベルをパイロット信号検出部２１で検出して冷凍機障害の程度を判定する。
冷凍能力の一時的低下のように冷凍機の軽度な故障であれば、超伝導フィルタ１１の通過特性（周波数特性）は温度上昇により一旦低周波側にずれるが、正規の温度に戻るため通過特性も正規の特性に戻る。すなわち、一時的な温度上昇により超伝導フィルタ１１の通過特性は図９（Ｂ）の点線に示すようになり、しかる後、正規温度への復帰により実線の通過特性に戻る。このため、図１０（Ａ）に示すように、温度上昇時には、まず周波数ｆＣ２のパイロット信号Ｓｆｃ２が検出され、ついで、周波数ｆＣ１のパイロット信号Ｓｆｃ１が検出され、一方、温度復帰時には、まず、周波数ｆＣ１のパイロット信号Ｓｆｃ１が検出されなくなり、ついで、周波数 ｆＣ２のパイロット信号Ｓｆｃ２が検出されなくなる。尚、温度上昇がわずかであれば、超伝導フィルタ１１の通過特性は図９（Ｃ）の点線で示すようになり、周波数ｆＣ１のパイロット信号Ｓｆｃ１は検出されず、パイロット信号Ｓｆｃ２のみ検出されその検出レベル時間波形は図１０（Ｂ）のようになる。
一方、重度の故障であれば、超伝導フィルタ１１の通過特性（周波数特性）は温度上昇により図９（Ｄ）の点線に示すように、周波数ｆＣ１，ｆＣ２より低周波側にずれっぱなしになる。このため、図１０（Ｃ）に示すように、温度上昇時に、まず周波数ｆＣ２のパイロット信号Ｓｆｃ２が検出され、ついで、周波数ｆＣ１のパイロット信号Ｓｆｃ１が検出され、更に温度が上昇して、まず、周波数ｆＣ２のパイロット信号Ｓｆｃ２が検出されなくなり、ついで、周波数ｆＣ１のパイロット信号Ｓｆｃ１が検出されなくなる。
パイロット信号検出部２１は、パイロット信号Ｓｆｃ１，Ｓｆｃ２の成分を取り出し、一定時間毎の各パイロット信号レベルをサンプリングし、各パイロット信号の検出レベルの時間波形に基づいて障害の程度を検出する。このようにすれば、障害の程度に応じて作業員派遣の優先順位をつけることができたり、故障原因特定のフィードバックにも役に立たせることが可能となる。
（Ｅ）第５実施例
図１１は本発明の第５実施例の構成図であり、冷凍機の故障及び低雑音増幅器の故障を検出するもので、図１の第１実施例と同一部分には同一符号を付している。第５実施例では、超伝導フィルタ１１と低雑音増幅器１２の中間に方向結合器４１を設け、該方向結合器を介してパイロット信号発生装置４２から出力するパイロット信号を超伝導フィルタ１１の出力信号に重畳する。パイロット信号の周波数ｆＬは超伝導フィルタ１１の通過帯域外の周波数であり、例えばｆＬ＝２０００ＭＨｚである。方向結合器４１は図１２に示す構成を備え、パイロット信号発生装置（発振器）４２より出力するパイロット信号を超伝導フィルタ１１と低雑音増幅器１２の各方向に流し込むように結合する。
正常時、印加されたパイロット信号ＳｆＬは低雑音増幅器１２で増幅され、アンテナ受信信号とともに出力端１８ａから出力される。パイロット信号検出部４３は、パイロット信号のレベルを検出し、該パイロット信号レベルに基づいて低雑音増幅器１２の異常をチェックする。すなわち、低雑音増幅器１２に故障が発生するとパイロット信号ＳｆＬの検出レベルが低下するから該パイロット信号レベルに基づいて低雑音増幅器の異常をチェックする。
ところで、超伝導フィルタ１１に通過帯域外のパイロット信号を入力すると、超伝導フィルタ１１が正常動作していれば、図１３に示すようにリターンロス（Ｓ１１（Ｔ＝７０Ｋ）参照）がほぼ０ｄＢなので、図１４（Ａ）に示すようにパイロット信号は超伝導フィルタ１１で全反射する。しかし、冷凍機の故障で温度が臨界温度よりも大きくなって超伝導状態でなくなると、図１３に示すようにリターンロス（Ｓ１１（Ｔ＝３００Ｋ）参照））は、−１０ｄＢ〜−２０ｄＢとなる。このため、図１４（Ｂ）に示すようにパイロット信号は超伝導フィルタ１１で１０％〜１％しか反射されなくなり、残りの９０％〜９９％は超伝導フィルタ内に吸収されて熱となる。
以上より、超伝導フィルタ１１が正常動作している場合、パイロット信号は結合器４１から超伝導フィルタ１１に流れ込もうとしても、全反射されて低雑音増幅器１２側に流れ込み、パイロット信号の全電力が低雑音増幅器１２に流れ込む。しかし、冷凍機１５の故障で臨界温度よりも大きくなると、パイロット信号は反射されずに超伝導フィルタ１１に流れ込むため、低雑音増幅器１２に流れ込むパイロット信号電力は正常時の半分になる。すなわち、パイロット信号は結合器部４１で５：５に分離して超伝導フィルタ１１及び低雑音増幅器１２に流れるため、故障時、パイロット信号検出部４３におけるパイロット信号検出レベルは３ｄＢ分下がることになる。尚、温度上昇時に低雑音増幅器１２のゲインも低下するため、実際には該ゲイン低下分も含めて５ｄＢ程度レベルが低下する。このレベル低下分は、結合器及び低雑音増幅器の特性から既知の値となるから以後ＬＤ（ｄＢ）とする。
パイロット信号検出部４３はパイロット信号レベルがＬＤ（ｄＢ）下がったか否かの判定を常時行っており、例えばＬＤ（ｄＢ）下がれば冷凍機１５に故障が発生したものとしてアラーム信号ＡＬＭを出力する。また、ＬＤ（ｄＢ）より大きなレベル低下が発生すれば低雑音増幅器１２に障害が発生したものとしてアラーム信号を出力する。
（Ｆ）第６実施例
図１５は本発明の第６実施例の構成図であり、第２実施例と第５実施例を組み合わせ、冷凍機の故障及び低雑音増幅器の故障を精度良く検出できるようにしたもので、第２、第５実施例と同一部分には同一符号を付している。第６実施例はパイロット信号として、▲１▼パイロット信号発生部３２より発生する周波数ｆｃ（＝１９００ＭＨｚ）の冷凍機障害検出用のパイロット信号Ｓｆｃ、▲２▼パイロット信号発生部４２より発生する周波数ｆＬ（＝２０００ＭＨｚ）の低雑音増幅器障害検出用のパイロット信号ＳｆＬを使用する。
アンテナ受信信号、周波数ｆｃのパイロット信号Ｓｆｃ、周波数ｆＬのパイロット信号ＳｆＬはそれぞれ出力端子１８ａから出力し、周波数ｆｃのパイロット信号検出部２１および周波数ｆＬのパイロット信号検出部４３の順に通過する。それぞれの検出部２１，４３は周波数ｆｃ，ｆＬのパイロット信号レベルを検出して障害箇所判定部５１に入力し、障害箇所判定部５１は図１６に従って障害箇所を判定する。すなわち、障害箇所判定部５１は周波数ｆｃのパイロット信号Ｓｆｃを検出しなければ、冷凍機１５は正常であると判定し、周波数ｆｃのパイロット信号Ｓｆｃを検出すれば冷凍機１５に障害が発生したと判定する。また、障害箇所判定部５１は、（１）パイロット信号ＳｆＬの検出レベルが正常であれば正常と判定し、（２）冷凍機が正常でパイロット信号ＳｆＬの検出レベルがＬＤ（ｄＢ）低下すれば、低周波増幅器１２に障害が発生したと判定し、（３）冷凍機が正常でパイロット信号ＳｆＬの検出レベルが任意ｄＢ低下すれば、低周波増幅器１２に障害が発生したと判定し、（４）冷凍機が異常でパイロット信号ＳｆＬの検出レベルがＬＤ（ｄＢ）低下すれば、低周波増幅器１２は正常であると判定し、（４）冷凍機が異常でパイロット信号ＳｆＬの検出レベルがＬＤ（ｄＢ）以上低下すれば、低周波増幅器１２も異常であると判定する。
以上より、第６実施例によれば、冷凍機が故障なのか、低雑音増幅器が故障なのか、両方故障なのかをより確実に検出でき、必要最低限の故障部品だけ交換すれば良いというメリットがある。特に、ＬＤ（ｄＢ）下がった場合、たまたま低雑音増幅器が故障してＬＤ（ｄＢ）下がっただけなのか、冷凍機が故障してＬＤ（ｄＢ）下がったのか原因を特定できる。
（Ｇ）第７実施例
以上では低雑音増幅器１２を真空容器内に納めて超伝導フィルタ１１と一緒に冷却したが、各実施例において低雑音増幅器１２は必ずしも冷却する必要はなく、筐体１６の外部に設けることができる。図１７は第２実施例（図６参照）の低雑音増幅器１２を筐体１６の外部に配置した例であり、５０は超伝導フィルタ装置である。
以上本発明によれば、冷凍機の故障の有無、故障内容、故障の程度を判定、報告することができ、移動体通信の通信不能という状況を最小限に押えることができる。
また、本発明によれば、冷凍機の障害を素早く、確実に検出でき、しかも、ハードウェア手段としてパイロット信号挿入手段及びパイロット信号検出手段を必要とするだけでよいため超伝導フィルタ装置及び無線受信増幅装置の小型軽量化が可能である。
また、本発明によれば、冷凍機、低雑音増幅器のいずれに障害が発生したのか、あるいは両方に障害が発生したのかを確実に検出することができる。
【図面の簡単な説明】
図１は本発明の無線受信増幅装置の構成図である。
図２は超伝導フィルタの通過特性図である。
図３は超伝導フィルタの通過特性及び損失特性の温度依存性説明図である。
図４は温度上昇時におけるパイロット検出レベルの時間波形図である。
図５は冷凍機の故障程度とパイロット検出レベル時間波形との関係説明図である。
図６は本発明の第２実施例の構成図である。
図７は本発明の第３実施例の構成図である。
図８は本発明の第４実施例の構成図である。
図９は２波のパイロット信号を用いて冷凍機の故障程度を検出する場合の通過特性説明図である。
図１０は２波のパイロット信号を用いて冷凍機の故障程度を検出する場合の検出レベルの時間波形である。
図１１は本発明の第５実施例の構成図である。
図１２は方向結合器の構成、動作説明図である。
図１３は超伝導フィルタの極低温時と高温時における通過特性Ｓ２１／反射特性Ｓ１１の説明図である。
図１４は第５実施例の障害箇所検出原理説明図である。
図１５は本発明の第６実施例の構成図である。
図１６は各パイロット検出レベルと障害箇所の対応説明図表である。
図１７は低雑音増幅器を筐体の外部に配置した超伝導フィルタ装置の構成図である
図１８は超伝導フィルタを備えた従来の無線受信増幅装置の構成図である。
図１９は超伝導フィルタの説明図である。
図２０は真空容器内における電気接続構成図である。
図２１は低雑音増幅器のゲイン特性、雑音指数特性である。Technical field
The present invention relates to a superconducting filter device used in a mobile communication base station and a radio reception amplifying device including the superconducting filter, and more particularly, to a superconducting filter device and a superconducting filter device capable of quickly detecting an abnormality in a refrigerator. The present invention relates to a radio reception amplifying device including a conduction filter.
Background art
In general, in order to obtain a steep cut-off characteristic in a communication filter, the number of filter stages must be increased. However, there is a problem that the loss in the pass band becomes large accordingly. Therefore, focusing on the fact that superconductors are 2 to 3 orders of magnitude lower in resistance than ordinary metals, superconducting filters that use superconductors as filter conductors to minimize loss in the passband are practical. It has become. In recent years, such superconducting filters have attracted attention for the purpose of effective use of frequencies in mobile band communications, increase in subscriber capacity, increase in the coverage area of base stations, and the like. YBCO (Y-Ba-Cu-O) having a critical temperature (Tc) of about 90K is known as a superconductor material for a superconducting filter, and is used at a Tc of about 70K where characteristics are stable.
FIG. 18 is a configuration diagram of a conventional radio reception amplifying apparatus provided with a superconducting filter. A superconducting filter (SCF) 1 and a low noise amplifier (LNA) 2 are fixed on a call head (cooling end) 4 and accommodated in a vacuum vessel 3. The call head 4 is cooled by the refrigerator 5, and the superconducting filter 1 and the low noise amplifier 2 are cooled by the refrigerator 5 through the call head 4 and operate at Tc = 70K. It has become. The vacuum vessel 3 and the refrigerator 5 are disposed in a housing 6 so that they can be installed outdoors. Between the terminals 7a and 7b and between the terminals 8a and 8b provided on the housing 6 and the vacuum vessel 3, coaxial cables 9a and 9b are provided. The terminal 7b → the superconducting filter 1 → the low noise amplifier 2 → the terminal 8b is also connected by the coaxial cable 9c.
As shown in FIGS. 19A and 19B, the superconducting filter 1 has a filter electrode 1b and an n-stage (n = 5 in the figure) λ / 2 resonance on a MgO substrate 1a having a thickness t = 0.5 mm. The vessel 1c is patterned with a YBCO film and sealed with an aluminum alloy package 1d. The package 1d prevents electromagnetic field leakage, thereby cooling the filter substrate 1a uniformly. FIG. 19A is a plan view with the top lid 1e of the package removed, and FIG. 19B is a cross-sectional view taken along line AA in FIG. 1f and 1g are coaxial connectors, and 1h is a ground formed by a YBCO film having a thickness of 0.4 μm.
The electrical connection configuration in the vacuum vessel is as shown in FIG. 20, and for example, two systems of radio reception amplification devices are formed. When the superconducting filter 1, 1 'is cooled to an extremely low temperature of 70K, the superconducting filter 1, 1' exhibits a predetermined passband characteristic, and outputs the passband component of the signals included in the received signals input from the input terminals 7b, 7b '. Low noise amplifiers (LNA) 2 and 2 'amplify the signal passing through superconducting filters 1 and 1' and send it out from output terminals 8b and 8b '. The low noise amplifiers 2 and 2 'have gain characteristics and noise figure characteristics shown in FIGS. The solid line is the characteristic at normal temperature (= 23 ° C.), and the dotted line is the characteristic at an extremely low temperature of 77 K. It can be seen that when the temperature is extremely low, the gain increases by about 2 dB and the noise figure (Noise Figure) decreases. That is, it is preferable to use the low noise amplifiers 2 and 2 'at an extremely low temperature rather than a normal temperature.
As described above, the superconducting filter 1 is housed in the vacuum vessel 3 and is operated by being cooled to a cryogenic temperature such as T = 70K by the refrigerator 5. In addition, the low noise amplifier (LNA) 2 that amplifies the received signal to a predetermined level can be reduced at a very low temperature, so that the noise figure can be reduced. Therefore, it is generally cooled simultaneously with the superconducting filter 1. A signal received by an antenna (not shown) is input to the housing 6 from the input end 7a via the antenna feeder, propagates through the coaxial cables 9a and 9c, and only a signal in a necessary frequency band is transmitted by the superconducting filter 1. It is taken out, amplified to a predetermined signal level by the low noise amplifier 2, and outputted from the output terminal 8a.
In the mobile communication system, the wireless receiver shown in FIG. 18 is installed outdoors such as the rooftop of a building, and is placed in a hot and humid adverse environment in midsummer. In such a severe condition, the wireless reception device is required to have reliability for long-time stable operation such as tens of thousands of hours. However, since many sliding parts are used for the refrigerator 5, there is a possibility of mechanical failure. When the refrigerator 5 breaks down, for example, the temperature maintained at T = 70K naturally rises, and the superconducting filter 1 cannot perform its original function, resulting in a state where communication is impossible. Therefore, when a failure occurs in the refrigerator, a function for immediately detecting and reporting the failure or a function for detecting and reporting the failure at a minor stage is required. Conventionally, there are those that detect the abnormality of the refrigerator by measuring the temperature in the vacuum vessel and monitoring whether the temperature exceeds the set temperature, but the equipment becomes large, the weight increases, and the size and weight are reduced There is a problem that does not match the requirements of
As described above, an object of the present invention is to provide a superconducting filter device and a wireless reception amplifying device that can detect a failure of a refrigerator quickly and reliably and that can be reduced in size and weight.
Another object of the present invention is to provide a superconducting filter device and a radio reception amplifying device capable of detecting a failure of a refrigerator and detecting the degree of the failure.
Another object of the present invention is to make it possible to reliably detect whether a failure has occurred in either the refrigerator or the low-noise amplifier, or whether both have failed.
Disclosure of the invention
The superconducting filter device of the present invention generates a superconducting filter exhibiting a predetermined passband characteristic when cooled to a cryogenic temperature, a refrigerator for cooling the superconducting filter to a cryogenic temperature, and a pilot signal outside the passband. A pilot signal generating unit that inputs the pilot signal to the superconducting filter together with the antenna reception signal, and a determination unit that determines abnormality of the refrigerator based on the level of the pilot signal included in the signal output from the superconducting filter . When the chiller fails and the temperature rises, the pass band of the superconducting filter moves to the low frequency side, the pilot signal frequency enters the pass band of the superconducting filter, and the pilot signal passes through the superconducting filter. . Therefore, it is possible to detect the abnormality of the refrigerator by monitoring whether the signal output from the superconducting filter includes a pilot signal. According to the present invention, the following effects can be expected.
(1) The trouble of the refrigerator can be detected quickly, and the superconducting filter device can be reduced in size and weight.
(2) By providing the pilot signal generating unit in the vicinity of the receiving antenna, for example, by providing the pilot signal radiating antenna in the vicinity of the receiving antenna, the pilot signal can be inserted into the received signal without loss and input to the superconducting filter.
(3) By inserting an isolator in the antenna feeder line, even if the pilot signal is reflected by the superconducting filter, it can be prevented from being radiated into the space from the antenna, and thereby it can be prevented from becoming an interference wave in other communication systems.
(4) The level of the pilot signal included in the signal output from the superconducting filter can be detected, and the degree of failure can be determined based on the detected level waveform, for example, based on the level change rate.
(5) Two pilot signals having different frequencies are generated and input to the superconducting filter, the level of each pilot signal is detected by the determination unit, and the degree of failure is determined based on each detected level waveform. it can.
(6) A low noise amplifier is connected to the superconducting filter, and both the superconducting filter and the low noise amplifier are cooled to a very low temperature so that a signal passing through the superconducting filter is amplified by the low noise amplifier and output. A reception amplification device can be configured.
A wireless receiver of the present invention includes a superconducting filter exhibiting a predetermined passband characteristic when cooled to an extremely low temperature, a low noise amplifier that amplifies a signal output from the superconducting filter, and the superconducting filter and the low noise amplifier. A refrigerator that cools to a low temperature, a pilot signal applying means that applies a pilot signal outside the pass band to the intermediate portion of the superconducting filter and the low noise amplifier, and a drop in the level of the pilot signal included in the signal output from the low noise amplifier is detected And a determination unit that determines that the refrigerator is abnormal when the level is lowered to a set level and determines that the low-noise amplifier is abnormal when the level is lowered to a level other than the set level.
If both the refrigerator (superconducting filter) and the low-noise amplifier are normal, half of the pilot signal applied from the pilot signal application means travels in the direction of the superconducting filter, and the pilot corresponding to the remaining half of the power. The signal part goes in the direction of the low noise amplifier. If the superconducting filter is operating normally, the pilot signal is all reflected and folded in the direction of the low noise amplifier, and eventually the total power of the pilot signal is input to the low noise amplifier. On the other hand, when the temperature rises due to the failure of the refrigerator, the pilot signal is absorbed by the superconducting filter and becomes all heat, and the power input to the low noise amplifier is halved. Therefore, the pilot signal level included in the signal output from the low noise amplifier differs between when the refrigerator is normal and when it is faulty, and when the fault occurs, the pilot signal level is lower than the normal level. As described above, the pilot signal level drop included in the signal output from the low noise amplifier is monitored, and when it falls to a predetermined level, it is determined that the refrigerator is abnormal, and when the level is lowered to a level other than the predetermined level, the low noise amplifier Judge as abnormal.
Further, another pilot signal is input to the superconducting filter, and an abnormality of the refrigerator is detected based on the detection level of the pilot included in the signal output from the low noise amplifier. In this way, it is possible to reliably detect the failure of the refrigerator, and reliably determine the abnormality of the low noise amplifier based on the reception level drop of the pilot signal applied to the intermediate part of the superconducting filter and the low noise amplifier. It becomes possible to do.
BEST MODE FOR CARRYING OUT THE INVENTION
(A) First embodiment
(A) Overall configuration
FIG. 1 is a configuration diagram of a radio reception amplifying apparatus according to the present invention. A superconducting filter (SCF) 11 and a low noise amplifier (LNA) 12 are fixed on a call head (cooling end) 14 and accommodated in a vacuum vessel 13. The inside of the vacuum vessel 13 is kept in a vacuum, and the outside air temperature is shut off. The call head 14 is cooled by the refrigerator 15, and the superconducting filter 11 and the low noise amplifier 12 are cooled by the refrigerator 15 via the call head 14 and operate at Tc = 70K. ing. The vacuum vessel 13 and the refrigerator 15 are arranged in a housing 16 so that they can be installed outdoors, and the housing 16 and the terminals 17a and 17b of the vacuum vessel 13 and 18a and 18b are connected by coaxial cables 19a and 19b. Similarly, the terminal 17b → the superconducting filter 11 → the low noise amplifier 12 → the terminal 18b is also connected by the coaxial cable 19c.
A receiving antenna 32 is connected to the input terminal 17a of the housing 16 via an antenna feeder 31, and a signal received by the antenna is input to the superconducting filter 11 via the input terminal 17a. The pilot signal generator 33 generates a pilot signal and superimposes the pilot signal on the antenna reception signal via the signal combiner 34. Therefore, the pilot signal is input to the superconducting filter together with the antenna reception signal. The frequency fc of this pilot signal is a frequency outside the pass band of the 70K superconducting filter 11.
A pilot signal detector 21 is connected to the output terminal 18a of the housing 16 so as to monitor whether or not the pilot signal is included in the signal output from the low noise amplifier 12, and to detect the level. The pilot signal detector 21 includes a directional coupler 21a that captures a part of the input signal, a bandpass filter 21b having a center frequency fc that passes the pilot signal, and a level detector 21c that detects the pilot signal level based on the bandpass filter output. I have.
(B) Principle of the present invention
When the superconducting filter 11 is cooled to an extremely low temperature of 70K, it exhibits a predetermined pass characteristic S21. FIG. 2 shows the T of the superconducting filter 11. 0 This is an example of pass characteristics at 70K, and has a pass band of 1950 MHz to 1970 MHz. The superconducting filter 11 is operated below the critical temperature (Tc), but the temperature is set to T = T as shown in FIG. 0 → T 1 → T 2 (T 0 <T 1 <T 2 ), The center frequency f of the filter passband 0 Is f 00 → f 01 → f 02 The insertion loss Loss increases, and the rate of change increases as the critical temperature Tc is approached. For this reason, the pass characteristic S21 of the superconducting filter 11 changes as shown in FIG. Actually, since the low noise amplifier 12 is connected immediately after the superconducting filter 11, the signal is amplified by the gain of the low noise amplifier 12. As a result, the total pass characteristic depends on the temperature as shown in FIG. ).
So T = T 0 A pilot signal having a frequency fc outside the filter pass band at (= 70 K) is input to the superconducting filter 11. However, the pilot signal frequency fc is set to be lower than the passband frequency. From the above, T = T 0 Since the pilot signal frequency fc is outside the pass band of the superconducting filter 11, the pilot signal Sfc is reflected by the filter portion and is not input to the low noise amplifier 12.
However, when the temperature T rises due to a failure of the refrigerator 15 or the like, the pass band of the superconducting filter 11 starts to shift to the low frequency side as shown in FIG. 3C, and gradually the pilot frequency fc becomes the pass band of the filter 11. Comes to include. As a result, pilot signal Sfc starts to pass through filter 11 (time t = t 1 ). The temperature further rises until the pilot frequency fc completely enters the pass band of the superconducting filter 11 (t = t 2 ), The pilot signal passing amount gradually increases. When the pilot frequency fc completely enters the pass band, the amount of pilot signal passing is almost constant, and when the temperature increases and the pilot frequency fc starts to enter the attenuation band of the superconducting filter (t = t 3 ) When the pilot signal passing amount gradually decreases and eventually completely falls outside the passband (t = t 4 ) The passing amount becomes zero. As a result, the pilot signal level input to the pilot signal detector 21 has a waveform as shown in FIG. 4 as time elapses.
From the above, the threshold level L TH If this value is exceeded, the pilot signal detector 21 determines that the frequency characteristic (pass characteristic) of the superconducting filter 11 has changed. That is, the pilot signal detector 21 has a detection level of the threshold level L. TH Is exceeded, it is determined that the refrigerator 15 has failed and a temperature rise has occurred, and an alarm signal ALM is output.
(C) Refrigerator failure detection
The superconducting filter 11 and the low noise amplifier 12 are fixed to the cooling end 14 and kept in a vacuum in the vacuum vessel 13 to block the outside air temperature. For example, the superconducting filter 11 is composed of a YBCO superconductor with Tc = 90K on a magnesium oxide MgO substrate, and a filter pattern with a passband of 1920 MHz to 1940 MHz is formed in a metal package of about 50 × 50 × 15 mm in size. Cool evenly. Operating temperature T 0 = 70K, the loss in the passband can be 0.1 dB or less. The refrigerator 15 is supplied with power from the outside (not shown), and is driven and controlled so that the filter operating temperature becomes 70 K by a driving power supply, a temperature controller, and the like (not shown). These are housed in a casing 16 having a size of about 500 × 500 × 300 mm, and are installed outdoors such as a rooftop of a building. For this reason, the internal temperature may be 60 ° C. to 80 ° C. during daytime in midsummer, and the refrigerator 15 is required to operate stably for a long time even under severe conditions.
A signal received from the antenna is input from the input terminal 17a, and only a signal in a desired frequency band passes through the superconducting filter 11, is amplified by the low noise amplifier 12, and is output from the output terminal 18a, and is a pilot signal detector. 21 to the next stage. Here, when a pilot signal (for example, fc = 1900 MHz) outside the filter band is applied to the received signal and input to the input terminal 17a, normal operation (T = T 0 ), As shown in FIG. 3C, the pilot frequency fc is outside the passband of the filter and is reflected by the filter portion. As a result, the pilot signal Sfc is not input to the low noise amplifier 12 and is not included in the output signal of the low noise amplifier.
However, when the refrigerator 15 breaks down and the temperature of the superconducting filter portion rises, the frequency characteristic starts to shift to the low frequency side, and the pilot signal begins to pass through the superconducting filter 11. The passed pilot signal is amplified by the low noise amplifier 12 and sent to the pilot signal detector 21. The pilot signal detection unit 21 extracts only the pilot signal component and samples the pilot signal level at regular time intervals. When the refrigerator 15 breaks down, the time waveform of the detection level shown in FIG. 4 is obtained. Therefore, when the detection level exceeds the threshold value, the pilot signal detector 21 outputs an alarm signal ALM indicating that the refrigerator is broken.
As described above, the pilot signal detection unit 21 samples and records the pilot signal detection level at regular intervals when the refrigerator fails (see FIG. 4), but the time waveform of the detection level depends on the temperature rise rate. The degree of change at the rise and fall and the threshold L TH The time span that exceeds is different. That is, in the case of a serious refrigerator failure, the temperature rise rate increases, and as shown in Case B in FIG. 5, the rise and fall of the time waveform of the detection level become steep, and the threshold value L TH The time span that exceeds is narrowed. On the other hand, in the case of a minor refrigerator failure, the rate of temperature rise is reduced, and as shown in Case C of FIG. TH The time span beyond is widened. Further, in the case of a moderate refrigerator failure, as shown in Case A of FIG. TH The time width exceeding C is intermediate between Cases B and C. As mentioned above, if the mechanism which identifies the waveform of Case A-C is mounted in the pilot signal detection part 21, the grade of the failure of a refrigerator will be known. That is, the degree of failure can be classified as Case B = severe, Case C = mild, Case A = average, and worker dispatching priorities can be set according to the degree of failure, It is also possible to use it for feedback of failure cause identification.
(B) Second embodiment
FIG. 6 is a block diagram of the second embodiment of the present invention, which has a preferable configuration for inserting a pilot signal into an antenna reception signal. The same parts as those in the first embodiment of FIG. Yes.
The pilot signal can be applied to the antenna reception signal using a coupler or the like as in the first embodiment, but the loss before the low noise amplifier 12 increases and the noise figure (NF) increases. The advantage of cooling the low noise amplifier 12 cannot be fully utilized. Therefore, a pilot signal generator 33 is installed in the vicinity of the receiving antenna 32 as shown in FIG. The pilot signal generator 33 includes an oscillator 33a that generates a pilot signal having a frequency fc outside the pass band of the superconducting filter 11, and a directional antenna 33b that radiates the pilot signal toward the reception antenna 32. The antenna 33b is directed toward and close to the receiving antenna 32. When the oscillator 33a oscillates in this state, a pilot signal is radiated toward the receiving antenna 32, and the antenna 32 receives the pilot signal together with a signal from the mobile station and inputs it to the signal input terminal 17a via the antenna feeder 31. As a result, the pilot signal can be superimposed on the received signal from the mobile station and input to the input terminal 17a without including extra loss as in the combiner, and the freezer can be used without increasing the noise figure (NF). Abnormalities can be detected.
(C) Third embodiment
FIG. 7 is a block diagram of the third embodiment of the present invention. Except for the point that the isolator 35 is provided between the receiving antenna 32 and the input terminal 17a of the housing 16, the second embodiment of FIG. The same components are denoted by the same reference numerals.
When the refrigerator 15 is operating normally, the pilot signal outside the pass band of the superconducting filter 11 is almost totally reflected by the filter portion, and the reflected pilot signal is radiated from the antenna 32. At this time, if the antenna 32 has directivity and gain, the reflected signal level may be radiated and radiated, which may be an interference wave for other communication systems. Therefore, in the third embodiment, the pilot signal reflected from the superconducting filter 11 is blocked by inserting the isolator 35 into the antenna feeder 31. According to the third embodiment, the reflected pilot signal is not radiated from the antenna and does not adversely affect other communications.
(D) Fourth embodiment
FIG. 8 is a block diagram of the fourth embodiment of the present invention, which has a configuration for inserting the first and second pilot signals into the antenna reception signal, and is the same as the second embodiment of FIG. Are given the same reference numerals. A pilot signal generator 33 arranged in the vicinity of the receiving antenna 32 has a frequency f. C1 First pilot signal Sfc of 1 Oscillator 33c generating frequency f C2 (> F C1 ) Second pilot signal Sfc 2 The oscillator 33d for generating the first and second pilot signals Sfc 1 , Sfc 2 Are combined, and an antenna 33f that radiates the first and second pilot signals toward the reception antenna 32 is provided.
If the refrigeration capacity of the refrigerator decreases due to long-term use (mild failure), the operating temperature of the superconducting filter 11 becomes T 0 It rises above (= 70K). However, when the ambient temperature of the refrigerator is lowered to about room temperature at night, the operating temperature of the superconducting filter 11 is T 0 Return to normal operation. On the other hand, the operating temperature of the superconducting filter 11 is T 0 (= 70K) It keeps rising above and the superconducting filter 11 cannot operate normally. If the degree of such failure can be detected, it is possible to take measures according to the degree of failure.
Therefore, as shown in FIG. 9A, T = T 0 The frequency f outside the passband of the superconducting filter 11 C1 , F C2 2 pilot signals Sfc each having 1 , Sfc 2 Are input to the superconducting filter 11 together with the received signal, and each pilot signal Sfc 1 , Sfc 2 Is detected by the pilot signal detector 21 to determine the degree of the refrigerator trouble.
If the refrigerator has a minor failure such as a temporary decrease in refrigeration capacity, the pass characteristic (frequency characteristic) of the superconducting filter 11 once shifts to the low frequency side due to the temperature rise, but returns to the normal temperature, so the pass characteristic. Will return to normal characteristics. That is, the passage characteristic of the superconducting filter 11 becomes as shown by the dotted line in FIG. 9B due to a temporary temperature rise, and then returns to the solid line passage characteristic by returning to the normal temperature. For this reason, as shown in FIG. C2 Pilot signal Sfc 2 Is detected, and then the frequency f C1 Pilot signal Sfc 1 On the other hand, at the time of temperature recovery, first, the frequency f C1 Pilot signal Sfc 1 Is not detected, and then the frequency f C2 Pilot signal Sfc 2 Will not be detected. If the temperature rise is slight, the pass characteristic of the superconducting filter 11 becomes as shown by the dotted line in FIG. C1 Pilot signal Sfc 1 Is not detected, pilot signal Sfc 2 Only the detected level waveform is detected as shown in FIG.
On the other hand, if it is a serious failure, the pass characteristic (frequency characteristic) of the superconducting filter 11 has a frequency f as shown by the dotted line in FIG. C1 , F C2 It shifts to the lower frequency side. For this reason, as shown in FIG. C2 Pilot signal Sfc 2 Is detected, and then the frequency f C1 Pilot signal Sfc 1 Is detected, and the temperature further rises. C2 Pilot signal Sfc 2 Is not detected, and then the frequency f C1 Pilot signal Sfc 1 Will not be detected.
The pilot signal detection unit 21 receives the pilot signal Sfc. 1 , Sfc 2 Are extracted, each pilot signal level is sampled at regular intervals, and the degree of failure is detected based on the time waveform of the detection level of each pilot signal. In this way, it is possible to prioritize the dispatch of workers according to the degree of failure, and it is also useful for feedback of failure cause identification.
(E) Fifth embodiment
FIG. 11 is a block diagram of the fifth embodiment of the present invention, which detects the failure of the refrigerator and the failure of the low noise amplifier. The same parts as those of the first embodiment of FIG. Yes. In the fifth embodiment, a directional coupler 41 is provided between the superconducting filter 11 and the low noise amplifier 12, and a pilot signal output from the pilot signal generator 42 via the directional coupler is used as an output signal of the superconducting filter 11. Superimpose on. Pilot signal frequency f L Is a frequency outside the passband of the superconducting filter 11, for example, f L = 2000 MHz. The directional coupler 41 has the configuration shown in FIG. 12, and couples the pilot signal output from the pilot signal generator (oscillator) 42 so as to flow in each direction of the superconducting filter 11 and the low noise amplifier 12.
When normal, the applied pilot signal Sf L Is amplified by the low noise amplifier 12 and output from the output terminal 18a together with the antenna reception signal. The pilot signal detector 43 detects the level of the pilot signal and checks the abnormality of the low noise amplifier 12 based on the pilot signal level. That is, when a failure occurs in the low noise amplifier 12, the pilot signal Sf L Therefore, the abnormality of the low noise amplifier is checked based on the pilot signal level.
By the way, when a pilot signal outside the pass band is input to the superconducting filter 11, if the superconducting filter 11 is operating normally, the return loss (see S11 (T = 70K)) is almost 0 dB as shown in FIG. The pilot signal is totally reflected by the superconducting filter 11 as shown in FIG. However, if the temperature is higher than the critical temperature and the superconducting state is lost due to the failure of the refrigerator, the return loss (see S11 (T = 300K))) is −10 dB to −20 dB as shown in FIG. . Therefore, as shown in FIG. 14B, the pilot signal is only reflected by 10% to 1% by the superconducting filter 11, and the remaining 90% to 99% is absorbed in the superconducting filter and becomes heat.
From the above, when the superconducting filter 11 is operating normally, even if the pilot signal tries to flow into the superconducting filter 11 from the coupler 41, it is totally reflected and flows into the low noise amplifier 12 side. Flows into the low noise amplifier 12. However, when the temperature exceeds the critical temperature due to the failure of the refrigerator 15, the pilot signal flows into the superconducting filter 11 without being reflected, so that the pilot signal power flowing into the low noise amplifier 12 is half that in the normal state. That is, since the pilot signal is separated into 5: 5 by the coupler 41 and flows to the superconducting filter 11 and the low noise amplifier 12, the pilot signal detection level in the pilot signal detector 43 is lowered by 3 dB at the time of failure. . Since the gain of the low noise amplifier 12 decreases when the temperature rises, the level actually decreases by about 5 dB including the gain reduction. Since this level drop is a known value from the characteristics of the coupler and the low noise amplifier, L D (DB).
The pilot signal detector 43 has a pilot signal level of L D (DB) It is always determined whether or not it has fallen, for example, L D (DB) If it falls, an alarm signal ALM is output as a failure of the refrigerator 15. L D (DB) If a greater level drop occurs, an alarm signal is output as a failure of the low noise amplifier 12.
(F) Sixth embodiment
FIG. 15 is a block diagram of a sixth embodiment of the present invention. The second embodiment and the fifth embodiment are combined so that a refrigerator failure and a low noise amplifier failure can be detected with high accuracy. 2 and the same part as 5th Example are attached | subjected the same code | symbol. In the sixth embodiment, (1) a pilot signal Sfc for detecting a refrigerator failure having a frequency fc (= 1900 MHz) generated from the pilot signal generator 32, and (2) a frequency f generated from the pilot signal generator 42 as pilot signals. L (= 2000 MHz) pilot signal Sf for detecting a low-noise amplifier fault L Is used.
Antenna reception signal, pilot signal Sfc of frequency fc, frequency f L Pilot signal Sf L Are respectively output from the output terminal 18a, and the pilot signal detector 21 having the frequency fc and the frequency f. L The pilot signal detectors 43 pass through in this order. Each of the detection units 21 and 43 has frequencies fc and f L The pilot signal level is detected and input to the fault location determination unit 51. The fault location determination unit 51 determines the fault location according to FIG. That is, if the failure location determination unit 51 does not detect the pilot signal Sfc of the frequency fc, it is determined that the refrigerator 15 is normal, and if the pilot signal Sfc of the frequency fc is detected, a failure has occurred in the refrigerator 15. judge. Further, the failure location determination unit 51 (1) pilot signal Sf L If the detection level is normal, it is determined to be normal. (2) The refrigerator is normal and the pilot signal Sf L Detection level is L D (DB) If decreased, it is determined that a failure has occurred in the low-frequency amplifier 12, and (3) the refrigerator is normal and the pilot signal Sf L If the detection level decreases by an arbitrary dB, it is determined that a failure has occurred in the low-frequency amplifier 12, and (4) the refrigerator is abnormal and the pilot signal Sf L Detection level is L D (DB) If it decreases, it is determined that the low frequency amplifier 12 is normal, and (4) the pilot signal Sf L Detection level is L D If it decreases by (dB) or more, it is determined that the low frequency amplifier 12 is also abnormal.
As described above, according to the sixth embodiment, it is possible to more reliably detect whether the refrigerator is malfunctioning, the low noise amplifier is malfunctioning, or both are malfunctioning, and it is only necessary to replace the minimum necessary malfunctioning parts. There is. In particular, L D (DB) If it goes down, it happens that the low noise amplifier fails and L D (DB) The refrigerator has broken down and it has just been lowered. D (DB) It is possible to identify the cause of the drop.
(G) Seventh embodiment
In the above, the low noise amplifier 12 is housed in a vacuum vessel and cooled together with the superconducting filter 11. However, in each embodiment, the low noise amplifier 12 is not necessarily cooled and can be provided outside the housing 16. . FIG. 17 shows an example in which the low noise amplifier 12 of the second embodiment (see FIG. 6) is arranged outside the casing 16, and 50 is a superconducting filter device.
As described above, according to the present invention, it is possible to determine and report the presence / absence of failure of the refrigerator, the content of the failure, and the degree of the failure, and it is possible to minimize the situation where communication of mobile communication is impossible.
In addition, according to the present invention, it is possible to quickly and surely detect the trouble of the refrigerator, and since only the pilot signal insertion means and the pilot signal detection means are required as hardware means, the superconducting filter device and the radio reception The amplification device can be reduced in size and weight.
In addition, according to the present invention, it is possible to reliably detect whether a failure has occurred in either the refrigerator or the low-noise amplifier, or whether a failure has occurred in both.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a radio reception amplifying apparatus according to the present invention.
FIG. 2 is a pass characteristic diagram of the superconducting filter.
FIG. 3 is an explanatory diagram of the temperature dependence of the pass characteristics and loss characteristics of the superconducting filter.
FIG. 4 is a time waveform diagram of the pilot detection level when the temperature rises.
FIG. 5 is an explanatory diagram of the relationship between the degree of failure of the refrigerator and the pilot detection level time waveform.
FIG. 6 is a block diagram of the second embodiment of the present invention.
FIG. 7 is a block diagram of the third embodiment of the present invention.
FIG. 8 is a block diagram of the fourth embodiment of the present invention.
FIG. 9 is an explanatory diagram of pass characteristics when the degree of failure of the refrigerator is detected using two-wave pilot signals.
FIG. 10 is a time waveform of the detection level when the degree of failure of the refrigerator is detected using two-wave pilot signals.
FIG. 11 is a block diagram of the fifth embodiment of the present invention.
FIG. 12 is a diagram for explaining the configuration and operation of the directional coupler.
FIG. 13 is an explanatory diagram of the pass characteristic S21 / reflection characteristic S11 of the superconducting filter at extremely low and high temperatures.
FIG. 14 is a diagram for explaining the fault location detection principle of the fifth embodiment.
FIG. 15 is a block diagram of the sixth embodiment of the present invention.
FIG. 16 is a table for explaining the correspondence between each pilot detection level and the fault location.
FIG. 17 is a configuration diagram of a superconducting filter device in which a low-noise amplifier is disposed outside the housing.
FIG. 18 is a configuration diagram of a conventional radio reception amplifying apparatus provided with a superconducting filter.
FIG. 19 is an explanatory diagram of a superconducting filter.
FIG. 20 is an electrical connection configuration diagram in the vacuum vessel.
FIG. 21 shows gain characteristics and noise figure characteristics of the low noise amplifier.

Claims (9)

超伝導フィルタ装置において、
極低温に冷却されたとき所定の通過帯域特性を示す超伝導フィルタ、
該超伝導フィルタを極低温に冷却する冷凍機、
前記通過帯域特性の通過帯域外であって低周波側の周波数を有するパイロット信号を発生し、該パイロット信号を超伝導フィルタにアンテナ受信信号と共に入力するパイロット信号発生部、
超伝導フィルタから出力する信号に含まれるパイロット信号が設定レベル以上になったとき超伝導フィルタシステムの異常を判定する判定部、
を備えたことを特徴とする超伝導フィルタ装置。In the superconducting filter device,
A superconducting filter that exhibits predetermined passband characteristics when cooled to cryogenic temperatures,
A refrigerator that cools the superconducting filter to a cryogenic temperature;
A pilot signal generating unit that generates a pilot signal having a low frequency side outside the pass band of the pass band characteristic , and inputs the pilot signal to the superconducting filter together with the antenna reception signal;
A determination unit for determining an abnormality of the superconducting filter system when a pilot signal included in a signal output from the superconducting filter exceeds a set level ;
A superconducting filter device comprising: 前記パイロット信号発生部を受信アンテナの近傍に設けたことを特徴とする請求項１記載の超電導フィルタ装置。  2. The superconducting filter device according to claim 1, wherein the pilot signal generator is provided in the vicinity of the receiving antenna. 前記パイロット信号発生部はパイロット信号放射アンテナを備え、該放射アンテナを前記受信アンテナ近傍に設けた、
ことを特徴とする請求項２記載の超伝導フィルタ装置。The pilot signal generator includes a pilot signal radiating antenna, and the radiating antenna is provided in the vicinity of the receiving antenna.
The superconducting filter device according to claim 2. アンテナフィーダ線にアイソレータが挿入された、
ことを特徴とする請求項２記載の超伝導フィルタ装置。An isolator is inserted in the antenna feeder line.
The superconducting filter device according to claim 2. 前記判定部は超伝導フィルタから出力する信号に含まれるパイロット信号のレベルを検出し、該検出レベル波形に基づいて異常の程度を判断する、
ことを特徴とする請求項１記載の超伝導フィルタ装置。The determination unit detects the level of a pilot signal included in the signal output from the superconducting filter, and determines the degree of abnormality based on the detection level waveform.
The superconducting filter device according to claim 1. アンテナにより受信された信号のうち所定帯域の信号を増幅して出力する無線受信増幅装置において、
極低温に冷却されたとき所定の通過帯域特性を示す超伝導フィルタ、
超伝導フィルタより出力する信号を増幅する低雑音増幅器、
該超伝導フィルタと低雑音増幅器を極低温に冷却する冷凍機、
前記通過帯域特性の通過帯域外であって低周波側の周波数を有するパイロット信号を発生し、該パイロット信号を超伝導フィルタにアンテナ受信信号と共に入力するパイロット信号発生部、
低雑音増幅器から出力する信号に含まれるパイロット信号が設定レベル以上になったとき超伝導フィルタシステムの異常を判定する判定部、
を備えたことを特徴とする無線受信増幅装置。In a radio reception amplification device that amplifies and outputs a signal in a predetermined band among signals received by an antenna,
A superconducting filter that exhibits predetermined passband characteristics when cooled to cryogenic temperatures,
Low noise amplifier that amplifies the signal output from the superconducting filter,
A refrigerator that cools the superconducting filter and the low-noise amplifier to a cryogenic temperature;
A pilot signal generating unit that generates a pilot signal having a low frequency side outside the pass band of the pass band characteristic , and inputs the pilot signal to the superconducting filter together with the antenna reception signal;
A determination unit for determining an abnormality of the superconducting filter system when a pilot signal included in a signal output from the low noise amplifier exceeds a set level ;
A radio reception amplifying apparatus comprising: 前記パイロット信号発生部はパイロット信号放射アンテナを備え、該放射アンテナを前記受信アンテナ近傍に設けた、
ことを特徴とする請求項６記載の無線受信増幅装置。The pilot signal generator includes a pilot signal radiating antenna, and the radiating antenna is provided in the vicinity of the receiving antenna.
The radio reception amplifying apparatus according to claim 6. アンテナフィーダ線にアイソレータが挿入された、
ことを特徴とする請求項７記載の無線受信増幅装置。An isolator is inserted in the antenna feeder line.
The radio reception amplifying apparatus according to claim 7. 前記判定部は低雑音増幅器から出力する信号に含まれるパイロット信号のレベルを検出し、該検出レベル波形に基づいて異常の程度を判断する、
ことを特徴とする請求項６記載の無線受信増幅装置。The determination unit detects a level of a pilot signal included in a signal output from a low noise amplifier, and determines the degree of abnormality based on the detection level waveform.
The radio reception amplifying apparatus according to claim 6.
JP2002566856A 2001-02-22 2001-02-22 Superconducting filter device and radio reception amplifying device Expired - Fee Related JP4267324B2 (en)

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